/*
 * EAP-PEAP common routines
 * Copyright (c) 2008-2011, Jouni Malinen <j@w1.fi>
 *
 * This software may be distributed under the terms of the BSD license.
 * See README for more details.
 */

#ifdef EAP_PEAP

#include "utils/includes.h"

#include "utils/common.h"
#include "crypto/sha1.h"
#include "eap_peer/eap_peap_common.h"

int
peap_prfplus(int version, const u8* key, size_t key_len,
             const char* label, const u8* seed, size_t seed_len,
             u8* buf, size_t buf_len)
{
    unsigned char counter = 0;
    size_t pos, plen;
    u8 hash[SHA1_MAC_LEN];
    size_t label_len = os_strlen(label);
    u8 extra[2];
    const unsigned char* addr[5];
    size_t len[5];

    addr[0] = hash;
    len[0] = 0;
    addr[1] = (unsigned char*) label;
    len[1] = label_len;
    addr[2] = seed;
    len[2] = seed_len;

    if (version == 0) {
        /*
         * PRF+(K, S, LEN) = T1 | T2 | ... | Tn
         * T1 = HMAC-SHA1(K, S | 0x01 | 0x00 | 0x00)
         * T2 = HMAC-SHA1(K, T1 | S | 0x02 | 0x00 | 0x00)
         * ...
         * Tn = HMAC-SHA1(K, Tn-1 | S | n | 0x00 | 0x00)
         */

        extra[0] = 0;
        extra[1] = 0;

        addr[3] = &counter;
        len[3] = 1;
        addr[4] = extra;
        len[4] = 2;
    } else {
        /*
         * PRF (K,S,LEN) = T1 | T2 | T3 | T4 | ... where:
         * T1 = HMAC-SHA1(K, S | LEN | 0x01)
         * T2 = HMAC-SHA1 (K, T1 | S | LEN | 0x02)
         * T3 = HMAC-SHA1 (K, T2 | S | LEN | 0x03)
         * T4 = HMAC-SHA1 (K, T3 | S | LEN | 0x04)
         *   ...
         */

        extra[0] = buf_len & 0xff;

        addr[3] = extra;
        len[3] = 1;
        addr[4] = &counter;
        len[4] = 1;
    }

    pos = 0;

    while (pos < buf_len) {
        counter++;
        plen = buf_len - pos;

        if (hmac_sha1_vector(key, key_len, 5, addr, len, hash) < 0) {
            return -1;
        }

        if (plen >= SHA1_MAC_LEN) {
            os_memcpy(&buf[pos], hash, SHA1_MAC_LEN);
            pos += SHA1_MAC_LEN;
        } else {
            os_memcpy(&buf[pos], hash, plen);
            break;
        }

        len[0] = SHA1_MAC_LEN;
    }

    return 0;
}

#endif /* EAP_PEAP */
